The curtain is a large, yellow barrier of tightly-woven plastic that will keep the potash in the harbour.

CBC reporter Jill Coubrough said winds on the lake Friday morning blew ice from the middle of the lake towards the harbour and delayed the work for a while, but officials still expected to complete the installation by the end of the day Friday.

She also reported that fishers got some good news Friday, that they will have access to the harbours even after the installation of the curtain.

Provincial officials said the curtains are weighted at the centre that can be pulled down to allow boats to cross over.

They also said there have been a number of diving expeditions in the past couple of weeks in the infected harbours, and they found one live mussel in Winnipeg Beach, indicating the molluscs can survive the winters, even under ice.

Effectiveness questioned

Installing the curtain is Manitoba's first step in a controversial effort to eradicate an infestation of invasive zebra mussels in Lake Winnipeg.

The province plans to dump tonnes of liquid potash into the water at four harbours on the lake.

​A number of critics, including scientists, fishers and boaters, are worried about the chemical's impact and its effectiveness.

The province admits the treatment has not been tried in open water, but maintains liquid potash is lethal for zebra mussels, and doesn't appear to hurt any other aquatic life, aside from native mussels.

Officials from Manitoba Conservation will install this curtain at the Winnipeg Beach harbour Friday to contain the liquid potash. (Catherine Dulude/CBC)

But people who live on the lake are worried about the economic impact on the fishing community.

Laurence Russin, who lives in the village of Dunnottar, south of Winnipeg Beach, said when he heard what the province was planning he was skeptical and even after community meetings with officials he is still doubtful.

"I felt that it was an exercise in futility because this is a very large lake ... and I know the currents in this lake are significant," he said, adding that the problem is likely larger than just the harbours being targeted.

Russin suspects the province feels it must be seen to be doing something.

"What the government has decided is, it's better to appear to be doing something [rather] than to not do anything" he said.

His concern is while the treatment won't be effective, it will put a 'huge burden' on the local fishing community.

"These people, in the first three or four weeks of the season, is when they catch the majority of their quotas for the spring," he said. "That is going to be extremely detrimental to a lot of businesses."